- Gillespie's Rotary Hydraulic Governor History.
- Marquette Hydraulic Governor History.
- Marquette Hydraulic Governor Operation Manual.
- The Curtiss Proportional Electric Governor Control System Manual
- Woodward Governor Company advertisement history.
- Woodward Governor Company advertisement history.
- Woodward Governor Company advertisement history.
- Woodward Governor Company advertisement history.
- Woodward Governor Company advertisement history.
- Woodward Governor Company advertisement history.